HTTP status codes are how servers speak. Learn to hear what they're actually telling you—from success to rejection to confusion.
1xx status codes are HTTP's way of saying 'hold on, I'm not done yet'—interim responses that keep the conversation open before the final answer arrives.
The Internet's way of saying 'yes, and here it is.' What 200 OK actually means, when to use it instead of 201 or 204, and why HTTP success doesn't guarantee business success.
The 201 status code is the server announcing a birth: something that didn't exist now does, and here's where to find it.
The HTTP status code for when success means silence. 204 tells clients 'I did what you asked, and there's nothing more to say.'
A 301 is a name change. A 302 is a forwarding address. That distinction determines whether search engines transfer your rankings or leave them behind.
The 304 status code is HTTP's way of saying 'you already have it.' How conditional requests let browsers validate cached content without re-downloading a single byte.
The 400 Bad Request error means the server wants to help but can't understand your request. Learn what causes it, how to return useful error messages, and when to use it versus other status codes.
The HTTP specification named it wrong. 401 means 'I don't know who you are.' 403 means 'I know who you are, and the answer is no.' Here's how to use them correctly.
Every 404 is a broken promise—someone expected to find something and didn't. Understanding what 404 really means, when to use it, and how to turn dead ends into helpful redirections.
The server understood your request perfectly—it just won't do it that way. How 405 errors reveal the difference between endpoints that don't exist and methods that aren't welcome.
The 408 error means the server waited for your request, but you never finished sending it. Learn why silence triggers this timeout and how to prevent it.
The 429 error means you're asking for too much too fast. Understanding rate limits isn't just about avoiding errors—it's about being a good citizen of shared infrastructure.
The 500 error is a server's confession of failure without explanation. Learn what actually breaks, how to find the real error hiding in your logs, and how to handle the mystery gracefully on both sides.
A 502 Bad Gateway means the server in front is fine—but the server behind it isn't responding correctly. Learn why this happens and how to fix it.
503 is a promise to the client: the server is temporarily unavailable but will recover. Learn when to use it, how Retry-After creates a contract for reconnection, and why this optimistic error is essential for graceful degradation.
A 504 isn't a crash—it's a gateway that stopped waiting. Understanding why patience runs out in distributed systems, and what to do about it.
このページは役に立ちましたか？